1. Field of the Invention
The invention relates to a multi-pass heat exchanger having a tube body and a bonnet, which is connected to the tubesheet of the tube body and in which at least one web for directing the liquid conveyed into the bonnet is arranged, the web being connected to the bonnet.
2. Description of the Related Art
Multi-pass heat exchangers are used in the chemical industry. In a 2-pass heat exchanger a web separates the liquid conveyed into the bonnet from the liquid conveyed out of the bonnet. By fitting a plurality of webs into the bonnet of a 4 or 6-pass heat exchanger, the liquid flow is deflected repeatedly in the bonnet and forced to pass the heat exchanger repeatedly. As a result, high flow velocities are achieved in the tubes, and good heat transfer is obtained.
For use with liquids present in the ultra-pure form, in particular for use in ultra-pure-water systems (WFI=Water for Injection), these designs cannot be used, since seals are required to seal off the webs, and these seals involve the risk of bacterial deposit and contamination. For this reason, heat exchangers having only one passage and twin tubesheets have been used for ultra-pure-water systems. The flow velocities in the tubes of such heat exchangers are correspondingly low and poor coefficients of heat transfer are obtained. The consequence is that these heat exchangers, although satisfactory from the point of view of sterility, require a large overall length in order to achieve satisfactory cooling of the liquid. Heat exchangers for sterile liquids which measure several meters in overall length are not uncommon.
Against this background, the object of the present invention is to develop a multi-pass heat exchanger that can be used for cooling liquid present in the ultra-pure state, in particular ultra-pure water.
This object is achieved by modifying a multi-pass heat exchanger to eliminate the seal between the web and tubesheet and to form a gap between the web and the tubesheet.
According to the present invention, a multi-pass heat exchanger for cooling ultra-pure liquids is provided, the multi-pass heat exchanger including a tube body having a tubesheet, a bonnet connected to the tubesheet, and at least one web for directing the liquid conveyed into the bonnet, a portion of the web being secured to the bonnet and dividing the bonnet into at least two chambers, and wherein the web is not secured to the tubesheet.
According to another aspect of the present invention, a multi-pass heat exchanger is provided, the multi-pass heat exchanger including a tube body having a tubesheet, a bonnet connected to the tubesheet, and at least one web for directing the liquid conveyed into the bonnet, a portion of the web being secured to the bonnet and dividing the bonnet into at least two chambers, wherein there is a gap between the web and the tubesheet.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objects and other advantages of the invention will be realized and attained by the method and apparatus particularly pointed out in the written description and claims as well as the appended drawings.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.